Contactless rotary switching apparatus

ABSTRACT

A contactless rotary switching apparatus comprised of a discshaped fixed yoke which is stationary and a rotary yoke arranged in parallel with each other, a magnet positioned between the yokes, the magnet having one magnetic pole end fixed to one of the yokes while the other magnetic pole end is made free but arranged to lightly contact the other of the yokes, a number of balls made of magnetic material are arranged in succession in the form of a circle on the free end face of the magnet between the magnet and the yoke which lightly contacts the free end of the magnet, a plurality of magneto-electric converting devices are arranged radially towards the circumference at the peripheral portion of the fixed yoke, and at least one arm provided at the peripheral portion of the rotary yoke so that the arm or arms are extended towards the said fixed yoke so that an end or ends of the arms will be moved towards and away from the magneto-electric converting devices during rotation of the rotary yoke.

United States Patent 1 June 20,1972

Kobayashi [54] CONTACTLESS ROTARY SWITCHING APPARATUS [72] inventor: Tunekazu Kobeyashi, Kawasaki Japan [73] Assignee: Denki Onkyo Co., Ltd., Tokyo, Japan [22] Filed: Sept. 17, 1970 2 1] Appl. No.: 72,937

3,366,908 1/1968 Weiss et al. ..338/32 R Primary Examiner-C. L. Albritton Attorney-James E. Armstrong and Ronald S. Cornell [57] ABSTRACT A contactless rotary switching apparatus comprised of a discshaped fixed yoke which is stationary and a rotary yoke arranged in parallel with each other, a magnet positioned between the yokes, the magnet having one magnetic pole end fixed to one of the yokes while the other magnetic pole end is made free but arranged to lightly contact the other of the yokes, a number of balls made of magnetic material are arranged in succession in the form of a circle on the free end face of the magnet between the magnet and the yoke which lightly contacts the free end of the magnet, a plurality of magneto-electric converting devices are arranged radially towards the circumference at the peripheral portion of the fixed yoke, and at least one arm provided at the peripheral portion of the rotary yoke so that the arm or arms are extended towards the said fixed yoke so that an end or ends of the arms will be moved towards and away from the magneto-electric converting devices during rotation of the rotary yoke.

11 Claims, 23 Drawing Figures PATENTEDJum I972 3. 671 ,874

SHEET 2 OF 4 CONTACTLESS ROTARY SWITCHING APPARATUS BACKGROUND OF THE INVENTION Conventional contact-provided rotary switches which have been employed in the tuners of television sets incur disadvantages such as poor contact due to wear of contact points and generation of chattering noise.

The object of the present invention is to provide a contactless rotary switching apparatus free from the said disadvantages.

SUMMARY The present invention provides a contactless rotary switching apparatus comprised of a disc-shaped fixed yoke made of magnetic material which is stationary, a rotary yoke made of magnetic material which is arranged in parallel with the said fixed yoke, an actuating means which causes the said rotary yoke to rotate while keeping it parallel with the said fixed yoke, a magnet which is positioned between the said fixed yoke and rotary yoke and one magnetic pole end of which is fixed to one of the said yokes and the other magnetic pole free end is made to lightly contact the rest of the said yokes, a plurality of magneto-electric converting devices, for example Hall effect devices and magneto-resistance devices, which are arranged in radial directions on the peripheral portion of the said fixed yoke, an external input power supply and external load connected to the said magneto-electric converting devices, an arm or arms made of magnetic material which are provided at the peripheral portion of the said rotary yoke, extending towards the said fixed yoke so that the end or ends of the said arm or arms will be in the proximity of the said magneto-electric converting devices, grooves which are provided'in the form of circle on the free end face of the said magnet and the end face of a yoke with which the said magnet comes in contact in reference to the center line of rotation of the said rotary yoke, and a number of balls made of magnetic material which are housed in the said grooves and couple the said magnet and the yoke which lightly contacts the said magnet so that they are kept rotatable.

BRIEF DESCRIPTION OF DRAWINGS The present invention is illustrated in detail in the accompanying drawings whereof:

FIG. 1 is a partially cutaway side view of the contactless rotary switching apparatus (hereinafier referred to as the apparatus") of one embodiment of the present invention;

FIG. 2 is a rear view of the fixed yoke of the apparatus;

FIG. 3 is a front view of the rotary yoke of the said apparatus;

FIG. 4 is a plan illustrating the shape of the arm end of the apparatus;

FIG. 5 is a cutaway side view of another embodiment of the apparatus of the present invention;

FIG. 6 is a rear view of the fixed yoke of the apparatus shown in FIG. 5; 1

FIG. 7 is a cross sectional view of another embodiment of the apparatus of the present invention;

FIG. 8 is a rear view of the fixed yoke of the apparatus shown in FIG. 7;

FIG. 9 is a front view of the rotary yoke of the apparatus shown in FIG. 7;

FIG. 10 is a rear view of another embodiment of a fixed yoke for the apparatus shown in FIG. 7;

FIG. 11 is a side view of another embodiment of the apparatus of the present invention;

FIG. 12 is a rear view of the fixed yoke of the apparatus shown in FIG. 1 1;

FIG. 13 is a side view of another embodiment of fixed yoke for the apparatus shown in FIG. 1 1;

FIG. 14 is a cross section of another embodiment of the apparatus of the present invention;

FIG. 15 is a front view of the fixed yoke of the apparatus shown in FIG. l4;

FIG. 16 is a front view of the rotary yoke of the apparatus shown in FIG. 14;

FIG. 17 is the front view of another embodiment of fixed yoke for the apparatus shown in FIG. 15;

FIG. 18 is a front view of another embodiment of the rotary yoke for the device shown in FIG. 16;

FIG. 19 is a front view of another embodiment of plate yokes actuating means for the apparatus shown in FIG. 14;

FIG. 20 is a cross sectional view of another embodiment of the apparatus of the present invention;

FIG. 21 is a rear view of the fixed yoke of the apparatus shown in FIG. 20; and

FIGS. 22a and 22b are front views of the rotary yokes of the apparatus shown in FIG. 20.

DETAILED DESCRIPTION Referring to FIGS. 1 to 3 of the drawings, there is shown a contactless rotary switching apparatus comprised of a discshaped fixed yoke 20 which is fixed to the front inside of housing 10, magneto-electric converting devices 30 fixed to fixed yoke 20, magnet 40 fixed to the central portion of fixed yoke 20, rotary yoke 50 which is provided to lightly contact the free end of the magnet 40, a plurality of balls 60 which are arranged between said rotary yoke 50 and magnet 40, and rotary shaft 70 as the actuating means which rotates aid rotary yoke 50.

Housing 10 mentioned above is made of non-magnetic material, to the front of which a number of terminals 11 are attached, and at the rear center of which aperture 12 is provided, and an external input power supply and external load, for example tuning circuit 13, are respectively connected to the said terminals.

Said fixed yoke 20 is disc-shaped and formed from magnetic material, at the rear peripheral portion of which magnetoelectric converting devices 30 are arranged radially at given equal intervals.

Each magneto-electric converting device 30 is comprised of a Hall effect device, a magneto resistance device, or an integrated circuit containing such devices, and is connected to external circuit 13 through said terminal 11. Fixed yoke 20 can be of the disc type but it is desirable to design the portions where magneto-electric converting devices 30 are to be fixed as radial projections 21 as shown in FIG. 2. Thus each magneto-electric device 30 is magnetically isolated to ensure accurate switching operation. Magnet 40 is in such relative position that one end with polarity S is fixed to the rear center of said fixed yoke 20 and its other end with polarity Nwhich is made free is projected toward the rear.

Since magnet 40 is ofien made of ferrite, reinforcing part 41 made of magnetic material with high wear resistance such as iron, etc. is attached to the projected magnetic pole end, that is, the free end, to prevent magnet 40 from wearing due to direct contact with rotary yoke 50.

Rotary yoke 50 made of a magnetic material is rotatably mounted onto the free end of magnet 40. Arm 5] is extended from the peripheral portion of rotary yoke 50 towards fixed yoke 20 and end 51a of this arm is oppositely in the proximity of said magneto-electric converting device 30 with a small 8 P- On both the front face of rotary yoke 50 and the free end face of magnet 40, circular grooves 42 and 52 with the same diameter from center of rotation O of rotary yoke 50 are are provided respectively.

Circular grooves 42 and 52 have the same width so that they form a tubular enclosure when rotary yoke 50 contacts magnet 40 wherein the said grooves are matched in opposite position. Balls 60, made of magnetic material, are housed in the tubular enclosure formed by grooves 42 and 52.

Balls 60 are given a diameter larger than the diameter of the tubular enclosure formed by the grooves; therefore, rotary yoke 50 is rotatably coupled to magnet 40 while there remains a small gap due to the balls. Rotary yoke 50 is biased towards magnet 40 by spring 14 attached to the rear inside of case 10 and is supported by spring 14 so that it does not come off from magnet 40.

Actuating means 70 is available in a variety of constructions. Referring to FIG. 1, it is simplest to attach rotary shaft 70 made of non-magnetic material to the rear of rotary yoke 50.

A dial and corresponding scale which are not illustrated are provided at the rear end of rotary shaft 70 and permit arm 51 of the rotary yoke to closely approach to the specified magneto-electric converting device.

It is desirable to bevel end 51a of arm 51 of rotary yoke 50 so that said end has a beveled surface in the direction of rotation as illustrated in FIG. 4. Thus, the ability of fine tuning can be obtained from variation of the magnetic flux density which is applied to magneto-electric converting devices 30 by slightly rotating arm 51 in the direction of the arrow when end 51a of arm 51 closely approaches magneto-electric converting device 30.

The apparatus according to the present invention is as described above. Rotation of arm 51 in accordance with rotation of rotary shaft 70 permits end 51a of the arm to approach magneto-electric converting devices in sequence, thereby enabling actuation of magneto-electric converting device 30 with concentration of the magnetic flux onto the magnetoelectric converting device when the end of the said arm closely approaches it. Accordingly, regarding the apparatus according to the present invention, rotation of rotary yoke 50 actuates circuit 13 connected to specified magneto-electric converting device 30 with concentration of magnetic flux onto the said magneto-electric converting device.

The apparatus according to the present invention is advantageous in the following points.

Since arm 51 is attracted to fixed yoke 20 and becomes stationary when the said arm of rotary yoke 50 closely approaches specified magneto-electric converting device 30, no other means is required for fixing the arm.

Poor contact and chattering noise does not occur in this apparatus because contacts are not employed.

Since magneto-electric converting device 30 can be manufactured in a small size, the entire apparatus can be compact and light. Because of magneto-electric converting device 30, the apparatus operates accurately, incurring fewer troubles.

With variation of the characteristics of magneto-electric converting device 30, switching operation as well as output voltage and current with different output characteristics can be obtained. Balls 60, made of magnetic material, positioned between the rotary yokes enable rotary yoke 50 to rotate while the magnetic path is closed.

Accordingly, the magnetic flux can be effectively utilized since the magnetic resistance of the magnetic path can be greatly reduced. Since balls 60 are used as the coupling means, rotary yoke 50 lightly rotates and there is no friction between magnet 40 and the rotary yoke; thus the service life of the apparatus is prolonged without deterioration of its performance.

FIGS. 5 and 6 illustrate the apparatus composed of rotary yoke 50, which is provided with two arms 51 and 51, and fixed yoke 20 provided with magneto-electric converting devices 30 at its periphery and which is provided with said balls 60 between fixed yoke 20 and magnet 40.

In this embodiment of the present invention, magnet 40 is fixed to rotary yoke 50 and balls 60 are housed in circular groove 22 of the fixed yoke and circular groove 42 of magnet 40. Arms 51 and 51' of rotary yoke 50 are extended parallel with the periphery of fixed yoke 20.

In this embodiment, it is advantageous that two magnetoelectric converting devices 30 and 30' be actuated at the same time with the rotation of rotary yoke 50.

As known from the said embodiment, there can be three or more arm 51 of the said rotary yoke.

FIGS. 7 to 13 illustrate an apparatus, rotary yoke 50 of which is provided with a plurality of arms. For example arms 51 and 51', which rotate tracing two concentric circles a and b with different diameters the center of which is center 0 of rotation of rotary yoke 50. Therefore, lengths l and I of said arms 51 and 51 in the radial direction in reference to center of rotation 0 can be different.

In this embodiment of the present invention, magneto-electric converting devices 30 and 30' which are to be mounted on fixed yoke 20 are arranged in opposite positions on loci a and b of said arms 51 and 51. Accordingly, not only can the number of magneto-electric converting devices 30 and 30' be increased but, also, two groups of magneto-electric converting devices 30 and 30' arranged on loci a and b can be used for different purposes, thus enabling accurate and complicated switching.

Arms 51 and 51 of rotary yoke 50 used in this embodiment of the invention are generally projected in the radial direction as illustrated in FIG. 9. In some cases, the said arms can be projected at an angle smaller than 180 as illustrated in FIG. 10 and the number of arms and rows of magneto-electric converting devices can be more than three. Said arm 51 or 51' can be extended so as to be parallel with the peripheral surface of fixed yoke 20 as illustrated in FIG. 11. Furthermore, one said arm can be designed to closely approach magneto-electric converting devices 30 and 30' arranged in more than two rows as illustrated in FIG. 13.

If designed as illustrated in FIG. 13, arm 51 can actuate two circuits l3 and 13' with different power supplies and loads at the same time. Since only magneto-electric converting device 30 operates when arm 51 reaches specified position P, if magneto-electric converting device 30' at specified position P is omitted, magneto-electric device 30 can be used to turn off the entire apparatus.

FIGS. 14 to 19 illustrate an apparatus composed of fixed yoke 20 which is provided with plate yokes which are of the strip type and which are provided with actuating means to incline the said plate yokes when desired. Said plate yokes 80 are radially attached to the front of fixed yoke 20 with pins 81 and are designed so that outward ends 83 of the said yokes rotate with pins 81 as the fulcrum by shifting inward ends 82 towards the circumference of the fixed yoke.

In this embodiment of the present invention, fixed yoke 20 is fixed to housing 10 by pin 23 thereby forming space 15 to house plate yoke 80 between fixed yoke 20 and housing 10.

For said actuating means 90, a hook can be inserted from the front of housing 10 so as to selectively rotate plate yoke 80, but it is desirable in use to combine said actuating means 90 with actuating means 70 as illustrated in FIG. 14.

Actuating means 90 illustrated in FIG. 14 is comprised of rotatable slide shaft 92 which is inserted into hole 91 passing through rotary shaft 70, rotary yoke 50, magnet 40 and fixed yoke 20 and of hook 93 which is projected at the end of said shaft 92 and is designed so that hook 93 disengages from plate yokes 80, when said slide shaft 92 is retreated, as illustrated in FIG. 14, and engages with one plate yoke 80 when said slide shaft is advanced.

To smooth movement of said slide shaft, it is desirable to form groove 24 around the opening of hole 91 of fixed yoke 20, wherein hook 93 can be housed when the slide shaft is retreated.

Furthermore, it is desirable that inward end 82 of plate yoke 80 is provided with U-shaped cut 82a to ensure engagement. The engaging means is not restricted, however, to the type mentioned mentioned above and any other suitable means such as gear type engaging means illustrated in FIG. 19 can be employed.

In this embodiment of the present invention, rotary yoke 50 is provided with arm 51 which is extended to closely approach fixed yoke 20 and arm 51" which is extended to closely approach plate yoke 80. Magnetoelectric convening devices 30 and 30" are provided at the ends of said fixed yoke 20 and plate yoke 80 opposite the said arms.

In this embodiment, as illustrated in FIGS. 14 to 16, mag neto-electric converting devices 30 of the fixed yoke and magneto-electric converting devices 30 of plate yokes 80 are actuated simultaneously by two arms 51 and 51" of rotary yokes 50. Depending on the purpose of use, as illustrated in FIGS. 17 and 18, three arms (51, 51 and 51") or more can be provided at rotary yoke '50, or one arm 51" of the three arms (51, 51 and 51") can be designed to become out of alignment with magneto-electric converting device 30", depending on the rotation angle of rotary yoke 50.

If the apparatus is designed as above, arms 51, 51 and 51" can actuate magneto-electric converting devices 30, 30' and 30" or specified'magneto-electric converting devices 30 and 30, at the specified rotation angle of the rotary yoke.

Since this embodiment of the present invention is such as mentioned above, magneto-electric converting devices 30 of the fixed yoke can be used for selection of channels and magneto-electric converting devices 30" of the plate yoke for fine tuning if the apparatus which is designed as illustrated in FIGS. 14 and 16 is used as the tuner of a television set. According to the embodiment illustrated in FIGS. 14 to 16, when rotary yoke 50 is rotated to cause arms 51 and 51" to approach specified magneto-electric converting devices 30 and 30", circuits l3 and 13", such as the tuning circuit, etc., which are connected to said devices 30 and 30" function.

When slide shaft 92 advances and rotates plate yokes 80 with hook 93, the position of magneto-electric converting device 30" of the plate yokes slightly deviates from arm 51" opposite thereto; accordingly, the area of said 30" which receives the magnetic flux varies and the quantity of the magnetic flux to be applied to magneto-electric converting device also varies.

Since operation of circuit 13" changes in accordance with variation of the quantity of magnetic flux, the apparatus enables fine tuning. Hereupon it is desirable to bevel the end of arm 51" which closely approaches the said plate yokes as illustrated in FIG. 4. The advantage of this beveling is the consequent possibility of finer tuning. Since plate yokes 80 are attracted by the fixed yoke, no other fixing means is required for the plate yokes.

FIGS. 20 through 23 illustrates an embodiment in which there are provided rotary yokes 50 and 50 which are rotatable independently of each other by actuating means 70 which cause the rotary yokes to rotate simultaneously or individually.

The number of rotary yokes can be varied. Thus there can be more than three, or it can be two as for example when the apparatus is to be used as a tuner.

Rotary yokes 50 and 50' shown in this embodiment of the present invention are respectively provided with arms 51 and 51'. These arms are given different lengths l and I so that the arms rotate with concentric circles a and b as their loci, and magneto-electric converting devices 30 and 30 are arranged on fixed yoke 20 so as to be opposite to said arms 51 and 51' on circles a and b as their loci.

Actuating means 70 is devised with rotary shaft 72, which is slid into hole 71 passing through the center of rotary yokes 50 and 50'; toothed surfaces 73 and 73' are provided on the holes of said rotary yokes; gears 74 and 74' are provided on rotary shaft 72 so that the teeth of the gears can mesh with the teeth on surfaces 73 and 73' when the rotary shaft advances; speed reduction transmitting means, for example gear train 76, which meshes with external clutching portion 75 of the rotary shaft when said rotary shaft 72 retreats; and coupling portion 77 which couples said gear train 76 to said rotary yoke 50'.

Said two rotary yokes 50 and 50' are provided with circular grooves 53 and 53' with the same diameter, the center of which is center 0 of rotation. Balls 60, made of magnetic material, are housed between their mating surfaces.

In other words, these two rotary yokes 50 and 50' are coupled by the same means which couples magnet 40 to the yoke which contacts the free end of the magnet.

This embodiment of the present invention has the construction described above. Therefore, since two rotary yokes 50 and 51' rotate simultaneously and approach specified magneto-electric converting devices 30 and 30', circuits l3 and 13 which are connected to magneto-electric converting devices 30 and 30 (for example, the voltage tuning type circuits provided with Varactor diode) can be actuated by concentrating the magnetic flux onto magneto-electric converting devices 30 and 30'.

Since rotary shaft 72 is coupled to speed reduction transmitting means 76 when rotary shaft 72 is retreated, one rotary yoke 50' only can be slightly shifted by rotating rotary shaft 72 and the quantity of the magnetic flux to be applied to the magneto-electric converting device 30' can be varied by changing the area of this magneto-electric converting device opposite to arm 51'.

In this embodiment of the present invention, accordingly, rotary yoke 50 enables selection of channels and rotary yoke 50', fine tuning.

I-lereupon magneto-electric converting device 30' can be used for all channels in common. In this case, as one magnetoelectn'c converting device 30' satisfies the requirement, it is not necessary to actuate rotary yokes 50 and 50' at the same time and it is satisfactory to design the apparatus so that rotary yoke 50 can be rotated 360 for selection of channels and rotary yoke 50' can be rotated within a given angle for fine tunmg.

In this case, accordingly, an actuating means can be provided to selectively actuate two rotary yokes 50 and 50'.

For this actuating means, the pipe-shaped rotary shaft is to be attached to rotary yoke 50' for fine tuning and the rotary shaft which rotates rotary yoke 50 for selection of channels can be mounted into the said pipe-shaped rotary shaft.

This actuating means can be referred to the construction illustrated in FIG. 14.

The speed reduction transmitting means should not always require gears and can employ a known means such as a speed reduction mechanism comprised of a friction wheel, pulley and belt, etc.

What we claim is:

1. A contactless rotary switching apparatus comprised of a. a disc-shaped fixed yoke made of magnetic material;

b. at least one rotary yoke made of magnetic material, and

arranged opposite to and parallel with said fixed yoke;

c. an actuating means which is capable of causing each said rotary yoke to rotate in parallel with the said fixed yoke;

d. a magnet arranged between the said fixed yoke and said rotary yokes, one magnetic pole end of which is fixed to one of said yokes, and the other magnetic pole end of which is arranged opposite to the other of said yokes as a free end;

e. a plurality of magneto-electric converting devices radially arranged at the peripheral portion of said fixed yoke;

f. an external load and power source electrically connected to each of said magneto-electric converting devices;

g. at least one arm made of magnetic material extended from each said rotary yoke towards said fixed yoke, the end of which arm can closely approach a magneto-electric converting device;

h. circular grooves provided in the free end of said magnet and in the end face of the yoke which comes in contact with said free end; and

i. a plurality of balls housed in said grooves coupling the free end of said magnet and the mating yoke.

2. A contactless rotary switching apparatus, according to claim 1, wherein projections are radially arranged at the periphery of the fixed yoke and said magneto-electric converting devices are attached thereto.

3. A contactless rotary switching apparatus, according to claim 1, wherein said magnet is provided with a reinforcing part made of magnetic material with high mechanical strength.

4. A contactless rotary switching apparatus, according to claim 1, wherein a plurality of rotary yokes are provided said rotary yokes having a plurality of arms extending therefore at different distances from the center of rotation of said rotary yokes, whereby said arms rotate along concentric circles with different diameters from the center of rotation, and wherein the fixed yoke is provided with magneto-electric converting devices correspondingly arranged in a plurality of rows.

5. A contactless rotary switching apparatus, according to claim 1, wherein the fixed yoke is provided with magnetoelectric converting devices which are arranged in a plurality of rows, and one arm of each said rotary yoke closely approaches a plurality of magneto-electric converting devices.

6. A contactless rotary switching apparatus, according to claim 1, wherein strip-shaped plate yokes are radially attached to the fixed yoke so that their outward ends project from the fixed yoke, said plate yokes are mounted on the fixed yoke at one position so that the projected outward ends of said plate yokes rotate, the magneto-electric converting devices are radially arranged at the periphery of said fixed yoke, the projected outward ends of said plate yokes are respectively provided with magneto-electric converting devices, an actuating means is provided so that said plate yokes can be selectively rotated, and a plurality of arms are provided at said rotary yokes so that one of the said arms selectively approaches closely to the magneto-electric converting devices on the plate yokes.

7. A contactless rotary switching apparatus, according to claim 1, wherein a plurality of rotary yokes are provided with circular grooves in their mating surfaces where balls made of magnetic material are housed to rotatably couple said rotary yokes, and the actuating means is capable of either selectively or simultaneously rotating said rotary yokes.

8. A contactless rotary switching apparatus, according to claim 7, wherein a plurality of rotary yokes are respectively provided with arms of difierent lengths from the center of rotation and the fixed yoke is provided with the magneto-electn'c converting devices opposite in a plurality of rows to said arms.

9. A contactless rotary switching apparatus, according to claim 7, wherein a plurality of rotary yokes are controlled so that the rotation angles are different, the fixed yoke is provided with at least one magneto-electric converting device in the range of the rotation angle of each rotary yoke and the actuating means is provided at the said rotary yokes to selectively rotate the rotary yokes.

10. A contactless rotary switching apparatus, according to claim 7, wherein at least one of the rotary yokes is coupled to the rotary shaft through a speed reduction transmitting means.

11. A contactless rotary switching apparatus, according to claim 1, wherein at least one arm at least one rotary yoke is beveled in the direction of rotation at its ends. 

1. A contactless rotary switching apparatus comprised of a. a disc-shaped fixed yoke made of magnetic material; b. at least one rotary yoke made of magnetic material, and arranged opposite to and parallel with said fixed yoke; c. an actuating means which is capable of causing each said rotary yoke to rotate in parallel with the said fixeD yoke; d. a magnet arranged between the said fixed yoke and said rotary yokes, one magnetic pole end of which is fixed to one of said yokes, and the other magnetic pole end of which is arranged opposite to the other of said yokes as a free end; e. a plurality of magneto-electric converting devices radially arranged at the peripheral portion of said fixed yoke; f. an external load and power source electrically connected to each of said magneto-electric converting devices; g. at least one arm made of magnetic material extended from each said rotary yoke towards said fixed yoke, the end of which arm can closely approach a magneto-electric converting device; h. circular grooves provided in the free end of said magnet and in the end face of the yoke which comes in contact with said free end; and i. a plurality of balls housed in said grooves coupling the free end of said magnet and the mating yoke.
 2. A contactless rotary switching apparatus, according to claim 1, wherein projections are radially arranged at the periphery of the fixed yoke and said magneto-electric converting devices are attached thereto.
 3. A contactless rotary switching apparatus, according to claim 1, wherein said magnet is provided with a reinforcing part made of magnetic material with high mechanical strength.
 4. A contactless rotary switching apparatus, according to claim 1, wherein a plurality of rotary yokes are provided said rotary yokes having a plurality of arms extending therefore at different distances from the center of rotation of said rotary yokes, whereby said arms rotate along concentric circles with different diameters from the center of rotation, and wherein the fixed yoke is provided with magneto-electric converting devices correspondingly arranged in a plurality of rows.
 5. A contactless rotary switching apparatus, according to claim 1, wherein the fixed yoke is provided with magneto-electric converting devices which are arranged in a plurality of rows, and one arm of each said rotary yoke closely approaches a plurality of magneto-electric converting devices.
 6. A contactless rotary switching apparatus, according to claim 1, wherein strip-shaped plate yokes are radially attached to the fixed yoke so that their outward ends project from the fixed yoke, said plate yokes are mounted on the fixed yoke at one position so that the projected outward ends of said plate yokes rotate, the magneto-electric converting devices are radially arranged at the periphery of said fixed yoke, the projected outward ends of said plate yokes are respectively provided with magneto-electric converting devices, an actuating means is provided so that said plate yokes can be selectively rotated, and a plurality of arms are provided at said rotary yokes so that one of the said arms selectively approaches closely to the magneto-electric converting devices on the plate yokes.
 7. A contactless rotary switching apparatus, according to claim 1, wherein a plurality of rotary yokes are provided with circular grooves in their mating surfaces where balls made of magnetic material are housed to rotatably couple said rotary yokes, and the actuating means is capable of either selectively or simultaneously rotating said rotary yokes.
 8. A contactless rotary switching apparatus, according to claim 7, wherein a plurality of rotary yokes are respectively provided with arms of different lengths from the center of rotation and the fixed yoke is provided with the magneto-electric converting devices opposite in a plurality of rows to said arms.
 9. A contactless rotary switching apparatus, according to claim 7, wherein a plurality of rotary yokes are controlled so that the rotation angles are different, the fixed yoke is provided with at least one magneto-electric converting device in the range of the rotation angle of each rotary yoke and the actuating means is provided at the said rotary yokes to selectively rotate the rotary yokes.
 10. A contactless rotary switching apparatus, accoRding to claim 7, wherein at least one of the rotary yokes is coupled to the rotary shaft through a speed reduction transmitting means.
 11. A contactless rotary switching apparatus, according to claim 1, wherein at least one arm at least one rotary yoke is beveled in the direction of rotation at its ends. 